Multi-element swab



Oct. 5, 1965 R. G. TAYLOR, JR

MULTI-ELEMENT SWAB Filed Dec. 30, 1963 FIG- 3 INVENTOR. AAWm fi 6. 7 4% 0A, JR

ATTORNEY United States Patent O 3,209,660 MULTI-ELEMENT SWAB Raymond G. Taylor, In, Santa Monica, Calif., assignor to Byron Jackson Inc., Long Beach, Calif., a corporation of Delaware Filed Dec. 30, 1963, Ser. No. 334,370 Claims. (Cl. 92180) The present invention relates to swabs and, more particularly, to a multi-element swab, wherein a plurality of rubber or rubber-like swabbing elements are supported in axially spaced relation along a central support so as to be moved longitudinally through a well pipe and remove fluid therefrom.

In the completion and work-over of wells, it is oftentimes the practice to swab the well in by removal of fluids standing in the well pipe. Various types of devices have heretofore been employed for swa'bbing well pipe, including wire reinforced swab cups, flexible swab disks and rubber plugs, all of these elements to some extent constituting pistons which travel in a stroke of up to many thousands of feet through the well pipe and which are thus subjected to severe operating conditions from the standpoint of wear and damage caused as the swab elements, under load, pass through pipe couplings.

Within the limitations imposed by the strength of the swab line employed to move the swab upwardly through the pipe and the capacity of the prime mover employed to raise the swab with a column of fluid supported thereby, it is desirable that a swab be capable of supporting a substantial column of fluid; but yet, in some areas, swab operators are reluctant to employ swabs wherein the elements are wire reinforced due to the possibility that destruction of the swab elements leaves wire fragments within the well. Such fragments potentially may interfere with subsequent operations to be performed in the well pipe, particularly in cases where the pipe in which the swab is to be employed is, in effect, the well casing which is cemented in place, as in the case of permanent well completions. Accordingly, present-day emphasis is upon swabs which may be characterized as all rubber, i.e., swabs which are composed of or substantially wholly of an elastomeric material. In the light of the foregoing, an object of the present invention is to provide a swab comprising a plurality of elastomeric elements supported upon a central support therefor and each capable of supporting a substantial column of fluid thereabove as the swab is being moved upwardly through the well pipe.

As a practical consideration, inasmuch as the swabs must move through long lengths of well pipe, i.e., several thousands of feet as noted above, it is important that the swab be so constructed that it will fall readily through the well pipe. Accordingly, it is another object of the invention to provide an elastomeric swab element which, while being capable of supporting a substantial column of fluid thereabove, is so constructed that it will readily move downwardly through the fluid.

Ideally, a swab must be quite versatile in the sense that it should efiectively seal with the Well pipe to enable lifting of a comparatively light fluid column, on the one hand, but yet should be sufficiently durable and structurally strong as to, when required, lift .a heavy column of fluid, on the other hand. It is, therefore, still another object of the invention to provide an elastomeric swab element having a structure whereby upon initial upward movement through the well pipe it will seal with the latter responsive to a light fluid load thereon, the element being so constructed that under heavier fluid loads it will deform so as to support a heavy column of fluid with a minimum amount of wear as the swab element moves upwardly through the well pipe.

Other objects and advantages of the invention will be hereinafter described or will become apparent to those skilled in the art, and the novel features of the invention will be defined in the appended claims.

In the accompanying drawing:

FIG. 1 is a view partly in longitudinal section and partly in elevation, showing a swab assembly made in accordance with the invention, the swab being run into a Well pipe;

FIG. 2 is a fragmentary longitudinal sectional view of the swab assembly of FIG. 1, showing the swab element in broken lines in an unloaded condition and in full lines deformed to support a light fluid column; and

FIG. 3 is a view like FIG. 2, but in full lines showing the swab element deformed to support a heavier fluid column.

Like reference characters in the several figures of the accompanying drawing and in the following detailed description designate corresponding parts.

Referring first to FIG. 1, there is illustrated a swab as sembly comprising a mandrel generally denoted at M, on which is disposed at multi-element swab unit generally denoted at S. The mandrel is a typical oil Well swabbing mandrel including a head 1 provided with a threaded neck 2 for connection to a sinker bar or rope socket of a conventional swab line. The mandrel M includes a nose 3 threadedly connected to the lower end thereof as at 4 and provided with a tapered seat 5. Extending lengthwise of the mandrel is a plurality of circumferentially spaced ribs 6 defining a flow passage t-herebetween, these ribs serving to centralize the swab unit S along the mandrel for relative longitudinal movement.

As the swab is being run into the well pipe or tubing T, as seen in FIG. 1, the swab unit will be held by fluid friction and friction with the tubing wall upwardly displaced along the mandrel, but upon upward movement of the mandrel through the fluid, the swab unit will come to rest on the seat 5 to prevent the flow of fluid downwardly through the swab unit as is well known in the art.

For illustrative purposes, the swab unit S is shown as comprising an inner metallic tubular core 10, having thereon a multiplicity of swab elements respectively designated 11, each being for-med wholly of rubber or elastomeric material and being bonded to the core 10. The swab unit S is shown as comprising a unitary molding including three axially spaced elements 11 united with the core 10. It will be appreciated, however, that the present invention contemplates any suitable number of such elements 11 and, indeed, contemplates a plurality of units S respectively composed of a desired number of elements 11 supported upon the mandrel M, as is well known in the art.

Each of the swab elements 11 is composed of an upper lip 12 and a lower body section 14. The lip and the body of the swab element are integral with each other and present a smooth, continuous outer surface for contact with the bore of the tubing. The lip and body mutually cooperate to acomplish the foregoing objectives, i.e., to enable ease of swab descent through fluid in the tubing T, initial sealing with the tubing responsive to light load and deformation to support a heavier fluid load as the swab is being moved upwardly through the tubing.

In order to facilitate the passage of the swab unit through the fluid as it is being run, each swab element 11 preferably has its lower body portion 14 of a diameter less than the inside diameter of the tubing to enable the ready passage of fluid therebetween, the body being preferably rounded at the bottom or lower end, and tapered and diverging upwardly throughout or substantially throughout its length to a diameter approximating but preferably less than the inside diameter of the pipe T, it being understood that typical oil field tubing varies somewhat in its inside diameter. The upper lip 12 also has an outside diameter approximating the tubing diameter and is preferably tapered at its outer periphery so as to constitute an upward and outward extension of the body 14, but, due to the provision of an annular space or chamber 15 between the inside diameter of the lip and an axially extended web of rubber or elastomeric material 16 spaced inwardly from the lip and bonded to the core 10, the lip 12 is free to flex inward. Similarly, the chamber 15 enables slight upward and inward fiexture of the intermediate body portion 13 should the same encounter a restriction in the tubing as the swab is lowered therein.

Referring to FIG. 2, light fluid load applied to the swab elements 11 will deform the lip 12 outwardly to effect a seal with the wall of the tubing T. However, it will be observed that the lip has a radial thickness, such that it is not easily worn away or damaged and, indeed, has substantial resilient resistance to moving into engagement with the tubing. In order to effect sealing contact of the lip 12 and the body 14 in the zone just beneath the lip with the tubing T, it will be observed that such zone of the body itself must be substantially deformed under fluid load, the body of rubber comprising both the lip 12 and the intermediate body section 13 effectively being deformed downwardly and fulcruming within the element in the region of the base of the chamber 15.

Referring to FIG. 3, it will be observed that responsive to a heavier fluid column, i.e., a load on the order of a normal swabbing load, not only the lip 12 and the adjacent lower body zone are deformed but also the subjacent or lower body section is deformed downwardly. Such downward deformation of the entire body 14 is believed to cause such stretching or tensioning of the rubber material in the region of the lip 12 (due to the fact that the rubber is bonded to its support or core 10) that the lip 12 may be so deformed as to be effectively pulled out of contact with the tubing. This is believed to account for the long life of the lips of swabs made in accordance with this invention and pulled through many thousands of feet of tubing without damage, notwithstanding the existence of couplings at frequent intervals forming an annular groove into which fluid pressure would otherwise force the lip and probably cause tearing.

It is preferred moreover that the body will so deform that a minimum amount of leakage therepast may occur to assure the presence of a lubricating film of fluid between the swab element and the tubing as the same is moving upwardly in the tubing. The result of maintenance of such a lubricating film is long swab life. In the event that the fluid loading of the swab is such a to cause complete sealing contact with the tubing wall by the rubber element without the benefit of a lubricating film, excessive wear will occur.

The present swab element is, accordingly, constructed in a manner calculated to resist deformation to the extent that a lubricating film may be maintained by preferably availing of the above mentioned structural characteristics and proportional relationships which, from tests of the swab in actual wells, appear to have accomplished the desired result. In this connection it will be noted with respect to the illustrated annular elastomeric body constituting the swab element that the lip 12 has an axial length (1) approximately /2 the radial width (w) thereof; the body 14 has a length (L) approximately and preferably at least /2 its diameter but not exceeding a length in excess of the diameter. It is desired in this connection that the body be so proportioned that it will deform as described above but is not so thin axially as to flex as would a disc.

While the specific details of the invention have been herein shown and described, changes and alterations may be resorted to without departing from the spirit of the invention as defined in the appended claims.

I claim:

1. A well swab comprising a central support having bonded thereon a plurality of axially spaced annular elastomeric elements, each of said elements including an upper lip spaced outwardly from the support and having a radial thickness greater than its length, and a lower body section having a length equal to at least one-half its diameter, and said body section being integral with said lip and being entirely deformable in the axial direction in a direction away from said lip.

2. A well swab as defined in claim 1, wherein said lip has a radial thickness approximately twice the axial length of said lip.

3. A well swab as defined in claim 1, wherein said lower body section has a length approximately one-half its diameter.

4. A well swab comprising a central support and an annular elastomeric element bonded on said support, said element including at one end a lip spaced outwardly from the support and having a diameter approximating that of a well pipe in which the swab is to be used and having a radial thickness greater than its length, and said element having at its other end and integral with said lip an elongated body section of a slightly reduced diameter and of a length at least as long as one-half its diameter, and said body section being entirely deformable in the axial direction in a direction away from said lip.

5. A well swab as defined in claim 4, wherein said lip has a radial thickness approximately twice the axial length of said lip.

6. A well swab as defined in claim 4, wherein said lower body section has a length approximately one-half its diameter.

7. A well swab unit comprising a central core adapted to be supported by a swab mandrel so as to be moved through Well pipe, said core having bonded thereon a unitary elastomeric molding including a multiplicity of axially spaced annular swab elements, said swab elements each having an elongated body section of a diameter less than the well pipe in which it is to be used, a section above and integral with said body section of larger diameter than said body section and having a lip projecting axially therefrom in spaced relation to said core, said lip having a radial thickness greater than its length, and said body section being entirely deformable in the axial direction in a direction away from said lip.

8. A well swab as defined in claim 7, wherein said body section has a length approximately one-half its diameter.

9. A well swab as defined in claim 8, wherein said body section tapers downwardly from said lip to the lower end of said body section.

10. A well swab unit comprising a central core adapted to be supported by a swab mandrel so as to be moved through a well pipe, said core having bonded thereon a unitary elastomeric molding including a multiplicity of axially spaced annular swab elements, said swab elements each having an elongated body section of a diameter less than the well pipe in which it is to be used, a section above and integral with said body section of larger diam- 5 eter than said body section and having a lip projecting References Cited by the Examiner axially therefrom in spaced relation to said core, said lip UNITED STATES PATENTS having a radial thickness greater than its length, said body 2 109 913 3/38 Th held 92 241 section further having a length approximately one-half its 2360577 10/44 Parrish diameter and a rounded lower end, said body section still 5 2 656 229 10/53 stillwagon 92 253 further tapering downwardly from said lip to the lower 2926976 3 /60 Bowerman 92 240 end of said body section, said body section being entirely 3:023:062 2 Waldrop 2 242 deformable in the axial direction in a direction away from said lip. KARL J. ALBRECHT, Primary Examiner. 

1. A WELL SWAB COMPRISING A CENTRAL SUPPORT HAVING BONDED THEREON A PLURALITY OF AXIALLY SPACED ANNULAR ELASTOMERIC ELEMENTS, EACH OF SAID ELEMENTS INCLUDING AN UPPER LIP SPACED OUTWARDLY FROM THE SUPPORT AND HAVING A RADIAL THICKNESS GREATER THAN ITS LENGTH, AND A LOWER BODY SECTION HAVING A LENGTH EQUAL TO AT LEAST ONE-HALF ITS DIAMETER, AND SAID BODY SECTION BEING INTEGRAL WITH SAID LIP AND BEING ENTIRELY DEFORMABLE IN THE AXIAL DIRECTION IN A DIRECTION AWAY FROM SAID LIP. 